[A case of urachal xanthogranuloma suspected to be a urachal tumor].

A 47-year-old female consulted our hospital with the chief complaints of lower abdominal pain and fever. There was a palpable mass in the lower abdomen. The patient had undergone oophorectomy by lower abdominal median incision. Ultrasonography, computed tomography, and magnetic resonance imaging (MRI) demonstrated a cystic mass above the bladder dome extending to the umbilicus, which was strongly suspected to be a urachal tumor. Enhanced T1 weighted MRI showed a mass enhanced by contrast media. Partial cystectomy with urachal resection was performed by lower abdominal median incision. The histological diagnosis was xanthogranuloma. This is the thirteenth case report of xanthogranuloma of the urachus in the Japanese literature.